1. Field of the Invention
The present invention relates to a device for detecting spatial position.
2. Description of the Related Art
Devices for detecting spatial position are known in the field of surgery, where they can be used to monitor surgical interventions. Such devices for detecting spatial position are disposed on the surgical instruments being used for the purpose of tracking them, and are therefore also referred to as trackers. Both active and passive trackers are known within this context.
The passive trackers have reflectors, which reflect light emitted by optical transmitters located in the operating room, wherein the light reflected by the reflectors is received, for example, by CCD cameras and, using the detected light spots, the relative position and orientation of the reflectors, and therefore of the instrument, in the room are calculated. Alternatively, the so-called active trackers are themselves equipped with suitable light sources, especially infrared LED's, wherein the light emitted by the active trackers is detected by corresponding tracking cameras situated in the operating room, from which, in turn, position and orientation in the room can be determined.
The essential factor is that the devices for detecting spatial position must be situated in a defined position in relation to the instrument. It is thus known to locate devices for detecting spatial position on the surgical instrument itself using a mounting device. These mounting devices are configured, for example, as screw clamps, which allow the mounting device to be firmly screwed to the instrument. Thus when the surgical instrument is moved, the device for detecting spatial position executes corresponding movements.
During an operation, however, care must be taken to ensure that the device for detecting spatial position always remains within the viewing angle of the tracking camera. Otherwise there is a risk that the movements executed by the surgical instrument will not be detected, resulting in a risk of injury to the patient.
However, with many types of surgical instruments it is necessary to rotate the surgical instrument around its longitudinal axis. When known devices for detecting spatial position are used, however, the instrument can be rotated only a few angular degrees around its longitudinal axis in one direction before it must be rotated a few angular degrees in the opposite direction so that the device for detecting spatial position always remains within the viewing angle of the tracking camera and is not positioned underneath the instrument and therefore outside of the viewing angle of the tracking camera, as would occur if it were rotated approximately 180 degrees around its longitudinal axis. This generally complicates the operation being performed.
Also known is a rotatable disposition of the mounting device around the longitudinal axis of the instrument. This makes it possible to rotate the surgical instrument freely around its longitudinal axis with one hand, while the other hand is used to hold the mounting device in such a way that the device for detecting spatial position always remains above the surgical instrument, within the viewing angle of the tracking camera in the operating room. Problematic with this technique, however, is reliably ensuring axial and radial immobilization to allow a precise detection of spatial position.